Strips of material of this type are used for manufacture of diapers and other absorbent products such as feminine napkins. The strip generally contains a particulate material of the type known as a Super Absorbent Polymer for use in absorbing and containing moisture. Additional particulate materials can also be included for example deodorants, baking soda and zeolite.
The strips are generally cut from a wider web of the above material so that each strip has a tendency to release the powder at the side edges which are cut from the wider web. Recent developments in this field have lead to thicker and more complex materials with an increased tendency to release powder on the manufacturing line. This is disadvantageous since it leads to loss of the valuable powder and more importantly the release of the powder into the atmosphere leads to an unacceptable manufacturing environment.
Commercially in the field, tapes have been manufactured of the type known as C-fold in which a strip is folded along two space fold lines to form a flat base onto which the particulate material is applied to be carried thereby and two overlying leaves each extending from a respective fold line, the leaves overlapping in the middle of the base so as to contain the particulate material. This tape is often formed on line with the assembly machinery. However the on line formation of the tape is becoming unacceptable due to the release of the powder on the line and due to the increase in speed which has become available with recently developed assembly machinery. The trend in this industry is therefore for the manufacturer of the end product to become merely an assembler of the various components with those components being supplied by other specialist manufacturers.
In PCT Patent application Publication WO95/03019 of Korma SRL published on Feb. 2.sup.nd 1995 is disclosed a method of manufacturing a strip of this type which uses a fluid absorbing powder in admixture with a heat actuable adhesive powder. The powders are retained between two layers which are of a fluid permeable material such as paper which allows penetration of the fluid to the powder. In addition to the above powders, there are added lines of adhesive between the layers which act to bond the layers together to form a web. The adhesive lines allow slitting of the web into separate strips at the adhesive lines to form strips which have the edges sealed by the adhesive. This arrangement has achieved some commercial success and is becoming accepted as a preferred construction for supplying the absorbent powder. However the construction requires additional material in the layers in view of the width of the adhesive lines which reduce the actual working width of the strip that is the area containing the powder.
In an alternative field, that is the use of water absorption tapes to block migration of moisture through cables such as fiber-optic cables, there is provided a further teaching concerning a technique for manufacture of a suitable strip or tape of this type. Thus in U.S. Pat. No. 5,246,770 (Bottiglione) assigned to Intissel SA and published Sept. 21.sup.st 1993 is disclosed a method of manufacturing a strip of this type which uses a water swellable powder in admixture with a heat actuable adhesive powder. The powders are retained between two layers one of which is dissolvable in water to allow access of the water to the powder. The heat actuable powder is used to seal the layers together to hold the powder in place. This technique using air laid paper for the layers was also in public use around the same time.